1. Field of the Invention
The present invention relates to seatbelt retractors included in seatbelt devices for protecting occupants inside vehicles and, more particularly, to a seatbelt retractor that is attached to a seat back of a reclining seat.
2. Description of the Related Technology
A seatbelt device mounted on a vehicle is to protect an occupant at the time of a vehicle collision and the like by restraining the occupant in a seat by a seatbelt pulled out from a seatbelt retractor. When acceleration higher than a predetermined value is applied in the horizontal direction at the time of the vehicle collision and the like, the seatbelt retractor detects the acceleration by an acceleration sensor, allows a lock mechanism of the seatbelt to operate, and thus makes it impossible to pull out the seatbelt. An inertial body using a ball or an independent inertial body is known as the inertial body used in the acceleration sensor.
Incidentally, when the seatbelt retractor that is provided with this kind of acceleration sensor is installed in a seat back of a reclining seat, a posture of the seatbelt retractor changes according to a reclining angle of the seat back, and the acceleration cannot be detected properly under this state. In response to this, the seatbelt device that is provided with the acceleration sensor capable of detecting the acceleration properly irrespective of the reclining angle of the seat back is known (refer to, for example, Japanese Patent Application Publication No. 2000-79867 and Japanese Patent Application Publication No. 2000-52921).
According to the seatbelt device described in Japanese Patent Application Publication No. 2000-79867 and Japanese Patent Application Publication No. 2000-52921, a cable advance/retreat device that allows a cable to advance/retreat by a length corresponding to a tilt angle of the seat back is arranged at a connection part between a seat back support arm that is provided projectingly from a seat cushion and a reclining rotary shaft, and, when the seat back tilts in the longitudinal direction, a sensor reference line of the acceleration sensor is controlled to face the vertical direction at all times by a cable hung between the cable advance/retreat device and a seatbelt retractor, so as to detect the acceleration properly.
Further, with the seatbelt retractor that is used in the seatbelt device described in Japanese Patent Application Publication No. 2000-79867 and Japanese Patent Application Publication No. 2000-52921, movement of an inertial body (sensor weight) of the acceleration sensor allows a ratchet lever (second lever) of the lock mechanism to turn upwardly, and allows a claw at the tip end of the ratchet lever to engage with teeth of a steering wheel (ratchet wheel) rotating with a spindle, so as to lock the steering wheel, and thus to prevent pull-out operation of the seatbelt.